The mucus secreting apparatus of the large airways in man and animals has been investigated by a variety of in vitro and in vivo techniques. The multiplicity of cell types present which may contribute secretions or modulate the secretory process has precluded investigation into cellular biochemistry and specific cellular secretory products. We have developed a simplified mucus secreting preparation by treating whole tracheal explants with Na2EDTA and removing surface epithelium containing the goblet cells as an intact sheet. This epithelium is then cultured separately from its underlying tissue which contains the submucosal glands and secretions from the two sources are analyzed separately. We have demonstrated differences in the mucous glycoproteins (MGP) secreted by these disparate secretory elements, and have demonstrated the synthesis and secretion of lysozyme from the human surface epithelium, an enzyme previously believed to arise from submucosal glands but not surface epithelial cells. Initial progress has also been made in isolating pure goblet cells using elastase treatment of the isolated surface epithelium. This research proposal concerns an extension of the above studies. The modulation of the secretion of MGP by goblet cells in response to autonomic agents and calcium iontophores will be assessed. Long term culture methods to maintain surface epithelium and goblet cells will be developed and quantities of secretory products collected. Procedures to isolate goblet cells will be refined to optimize cell yields. These studies will be carried out initially in cat trachea but will be extended to human tissue whenever possible. The development of systems to allow whole organ culture, culture of intact surface epithelium and culture of goblet cells will offer a full range of models to delineate the secretory mechanisms of goblet cells and compare them to other secretory elements.